//做一个二分查询
// 输入：已经排好序的数组arr，一个待查找的值data
// 输出 true,false/返回索引值，-1
function binarySearch(arr, data) {
    //1.设置指针
    let count = 0
    let lower = 0;
    let upper = arr.length - 1;
    while (lower <= upper) {
        let mid = Math.floor((lower + upper) / 2);
        if (arr[mid] < data) {
            lower = mid + 1;
            count++
        } else if (arr[mid] > data) {
            upper = mid - 1;
            count++
        } else {
            console.log(mid);
            console.log(count);
        }
    }
    console.log(-1)
    console.log(count);
}
const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
console.log('二分查找', binarySearch(arr, 7));